You can no way compare a state like Texas with PA. Ive been to other states hunting and trapping and the terrain, population, food sources, etc. are all different. Heck, a fella from Texas told me a fox could live on nothing but snakes and bugs in texas all year long.
Everyone has their own opinion. Mine is based on 35 years of years of hunting an trapping.
Not only me, but many close friends and families that trapping and hunting is a way of life.
In the 80s and most of the 90s, we had a good population of both reds and greys. We experienced a great 20 year run with consistent catches and called fox. Around 1997, we started consistently catching a few coyotes. By 2000 - 2002 our fox catches were a 3rd of what they were during that 20 year run. Including the greys. There have been many changes over the years that have contributed to the fox decline, but the coyote is the most obvious change.
Since then I've seen it fluctuate. When we see a couple years of lower coyote numbers, the following couple years are better for fox.
As far as fisher go, what makes you think that? I saw the population shift long before the fisher took hold in my area. Matter of fact, we have less fisher here now than we did 5 years ago. Maybe the coyote are getting them too?